AB0322 RELATIONSHIP BETWEEN PHYSICAL BALANCE ABILITY AND PHASE ANGLE OBTAINED BY BIOELECTRICAL IMPEDANCE ANALYSIS IN PATIENTS WITH RHEUMATOID ARTHRITIS
Authors: M. Tada, Y. Matsumoto, Y. Yamada, K. Mandai, N. Hidaka, T. Koike
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> We have reported that a decrease in phase angle (PhA), an index of cell membrane fragility, nutritional status, and muscle strength, measured by bioelectrical impedance analysis (BIA), is associated with falls in patients with rheumatoid arthritis (RA) [1]. Since a decline in physical balance ability is thought to be related to falls, assessing physical balance ability is important, and in recent years, assessment of physical balance ability has been included in the diagnostic criteria for sarcopenia. The PhA reflects muscle status and may be related to physical balance ability, but the relationship between physical balance ability and the PhA in RA patients is unclear. <h3>Objectives</h3> To examine the relationship between physical balance ability and the PhA in RA patients. <h3>Methods</h3> A cross-sectional analysis of 89 RA patients (78% female, mean age: 66.7±14.3 years) was performed. The PhA was evaluated at 50 kHz on a BIA device (MC-780A; TANITA, Japan). Assessment of physical balance ability was performed with a muscle function analyzer (BM-220; TANITA), which can assess physical balance ability based on changes in load during standing up from a chair. Of the indices obtained by the muscle function analyzer, lateral balance was evaluated by dividing the lateral directional variation value (Vx mm/sec) by the load variation value (Vw kg/sec) (Vx/Vw). The balance score, which is the score of the stability time (stable time) from the point after the maximum load value and Vx/Vw compared to the reference value, was also assessed. The associations of PhA with Vx/Vw being above the median and the z-score of Vx/Vw and of the balance score being above -0.5 were tested by logistic regression analysis, and the association between Vx/Vw and the PhA as continuous variables was tested by multiple regression analysis. The cutoff value of PhA for the balance score z-score of -0.5 was calculated by receiver-operating characteristic (ROC) curve analysis. <h3>Results</h3> Even after adjusting for covariates (sex, age, BMI, ADL, disease activity, and medication status), the PhA was significantly associated with Vx/Vw greater than the median [odds ratio (OR): 0.44, 95% confidence interval (CI): 0.19-0.995)] and z-score &gt; -0.5 (OR: 0.42, 95%CI: 0.19-0.93). Multiple regression analysis adjusted for covariates also showed that the PhA was significantly associated with Vx/Vw (β=-0.22, p=0.023). A balance score z-score ≥ -0.5 was significantly associated with a PhA above the 75th percentile (OR: 9.34, 95%CI: 1.45-60.1). The cutoff value of the PhA for a balance score z-score of -0.5 was 4.87° (AUC = 0.64, p = 0.32) for men and 4.30° (AUC = 0.78, p &lt; 0.001) for women. <h3>Conclusion</h3> The PhA may be associated with physical balance ability. <h3>Reference</h3> [1] Matsumoto Y, Tada M et al. The bioimpedance phase angle is more useful than sarcopenia as a predictor of falls in patients with rheumatoid arthritis: Results from a 2-y prospective cohort study. Nutrition, 2022;102:111729 <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.